Day 4: Head and Neck Lectures

Oral Cavity

• Extends from the lips to the palatoglossal arch

• Dorsally it is roofed by the hard palate rostrally and the soft palate caudally

• Teeth/tongue

Pata(palate)gloss(tongue)al arch

Fold of mucosa extending vertically from the soft palate to the tongue on left/right sides

Nasal Cavity

• Facial portion of the respiratory tract

• Extends from nares to choana

• Contains nasal conchae

• Warms + humidifies air and traps foreign particles

Choana

A point where the two nasal cavities join to form the nasopharynx (left and right side of nose combine)

Conchae

Small turbinate bones that support the olfactory mucous membrane + increase surface area in nasal cavity

Pharynx parts (3)

• Nasopharynx

• Oropharynx

• Laryngopharynx

Nasopharynx

Choana to palato(palate)pharyngeal(pharynx) arch

Oropharynx

Palatoglossal arch to palatopharyngeal arch

Laryngopharynx

Palatopharyngeal arch to pharyngeosophageal limen

Path of food

Oral cavity —> oropharynx —> laryngopharynx —> esophagus (not in larynx/trachea)

Path of air

External nares —> nasal cavity —> nasopharynx —> laryngopharynx —> larynx —→ trachea (no esophagus so stomach has air in it)

Nares in animals

The external and internal openings of the nasal passages that allow for breathing and smelling

What separates the oropharynx from the nasopharynx?

The soft palate

Bones of the skull

• Incisive

• Nasal

• Maxillary

• Zygomatic

• Fontal

• Parietal

• Temporal

• Occipital

• Mandibular

• Palatine

• Pterygoid

• Sphenoid

  • Basisphenoid

  • Presphenoid

Epiglottic cartilage

Above soft palate and allows air to move in larynx and then when one swallows, it allows food to not go into trachea

Joints of thea head

• Temporomandibular

• Atlanto-Occipital Joint

Temporomandibular

• Between the mandible and the temporal bone

• Adjacent to the zygomatic arch

Oral pharynx direction

Ventral towards soft palate

Nasopharynx direction

Dorsal towards soft palate

Larynx that’s ______ is connected by little bones to the ______.

cartilage, skull

Atlanto-Occipital joint

Between atlas (C1 vertebra) and the occipital bone

The _____ also contains sinuses.

skull

Sinuses

Air-filled spaces within the skull covered by mucous membran

Sinuses

• Increase the surface area for warming air

• Communicate with the nasal cavity

• Dogs and cats have a maxillary recess and a frontal sinus

What are the two major synovial joints of the head?

Temporomandibular and Atlanto-Occipital joint

Atlanto-occipital joint allows the animal to move head _____ and _____.

up, down

Maxillary recess

What dogs have (basically sinus)

Dental Formula

Used to track teeth based on the number, type, and location

Each tooth has a _____ and a _____.

crown, root

Root

Embedded in the jaw

Crown

The top, exposes part

The ______ connects the root and crown.

neck

Brachydont teeth

• For dogs

• Covered by enamel (above gumline)

• Stop growing once occlude with other dental arcade

Hypsodont teeth

• For horses

• Opposite of brachydont teeth

The Dental Formula is mainly based on the _____ vs. _____.

right, left

C 2/3 in Dental Formula

2 canines on top, 3 canines on bottom

Key for Dental Formula

I = incisors, C = canine, P = premolar, M = molar

Muscles of mastication

• Digastricus

• Medial and Lateral Pterygoids

• Masseter

• Temporalis

Carnassial/shearing teeth

• Used for tearing meat

• Upper P4 and lower M1

Digastricus

• Occipital bone (skull) to body of mandible

• Opens jaw

Medial and Lateral Pterygoids

• Pterygopalatine fossa (skull) to the medial surface of the mandible

• Closes jaw

Masseter

• Zygomatic Arch (skull) to the lateral surface of the mandible

• Closes jaw

In horses, teeth are constantly wearing dow and ______.

regrow

Temporalis

• Temporal fossa (skull) to mandible

• Closes jaw

Other muscles of head

• Orbicularis Oris

• Orbicularis Oculi

Orbicularis Oris

• Surrounds the mouth along the lips

• Helps move lips

Orbicularis Oculi

• Surrounds eye

• Closes eye

Tongue muscles

• Intrinsic muscle

• Extrinsic muscle

Digastricus is a different muscle of mastication because why?

It opens the jaw, the others close it

Intrinsic Muscles

Attachments are both within the same structure

Extrinsic Muscles

Attachments are not within the same structure (each attachment is from different locations)

What muscle opens the jaw/mouth?

Digastricus

4 Salivary Glands

• Parotid

• Mandibular

• Sublingual

• Zygomatic

Parotid

Base of the ear (not palpable)

Mandibular

Base of the jaw between the facial and maxillary veins (palpable)

Sublingual

Rostral to the mandibular salivary gland

Zygomatic

Medial to teh zygomatic bone between the eye and the pterygoid muscle

Zygomatic and parotid open the ______ cavity (cheek).

buccal

Mandibular and sublingual open under the base of the ______.

tongue

Lymph nodes

• Associated with lymphatic system —→ filers fluids

• Only palpable lymph nodes of the heads are the mandibular lymph nodes

Mandibular Lymph Nodes

Located just ventral to the mandibular salivary gland

The Tunics (layers of the eye) - 3 parts

• Fibrous Tunic

• Vascular Tunic

• Nervous Tunic

Fibrous Tunic

• Connective tissue

• Sclera

• Cornea

Vascular Tunic

• Connects to circulation

• Ciliary Body

• Choroid

• Iris

How do lymph nodes relate to antigens

They capture antigens—foreign substances like viruses, bacteria, or abnormal cells—from peripheral tissues

Nervous Tunic

• Allows for vision

• Retina

• Optic Nerve

Periorbita

• Cone shaped sheath of connective tissue

• Contains smooth muscles, vessels, and nerves

• The extraocular eye muscles run through it to insert on the skull

Vertebrae Anatomy

• Dorsal spinous process

• Paired lateral transverse processes

• Cranial and caudal articular processes

• Arch

• Body

Arch of vertebra parts (2)

• Pedicle

• Lamina

Pedicle

Ventral region connecting to body

Lamina

Dorsal region connecting to spinous process

Body of vertebrae

Intervertebral discs lie between adjacent vertebrae

Larynx

• Musclo-cartilaginous organ

• Guards entrance to the trachea

• Vocalization and regulates airflow

4 cartilages of the Larynx

• Epiglottis

• Thyroid

• Arytenoid (paired)

• Cricoid

How many cervical vertebrae do humans have?

7

Larynx function

To open/close and tense/relax vocal cords (vocalization and proper respiration)

4 major muscles of Larynx

• Cricoarytenoideus Dorsalis

• Cricoarytenoideus Lateralis

• Cricothyroideus

• Thyroarytenoideus

Axis vs. Atlas vertebrae

The atlas (C1) and axis (C2) are the top two vertebrae in the cervical spine, uniquely specialized to support the skull and enable head movement

Hyoid Apparatus

Connects bump of skull to Larynx

Tubular structures

• Esophagus

• Trachea

Esophagus

• Tube of smooth /skeletal muscle

• Part of digestive system that carries food from the mouth to stomach

Trachea

• Tube with cartilaginous rings that are connected by smooth muscle and connective tissue

• Part of the respiratory system that carries air to and from the lungs

Trachea is _____ to the esophagus.

ventral

Muscles of the neck

• Sternohyoideus

• Sternothyroideus

• Sternocephalicus

• Omotransversarius

• Brachiocephalicus

Superficial Cervical Lymph Node

• Only palpable lymph node in neck

• In front of shoulder and sits deep to the omotransversarius muscle

Palpable

Capable of being physically touched, felt, or examined by hand

Thyroid Gland

• Butterfly-shaped bilobed gland caudal to larynx; lateral to 1st 5 tracheal rings

• Parathyroid gland is associated with both lobes of thyroid gland

Thyroid gland secretes _____ that are important from metabolism and the regulation of calcium and phosphate balance.

hormones

Parathyroid gland secretes _____ that help regulate calcium and _____ levels.

hormones, phosphate

Blood vessels (2)

• Carotid artery

• External jugular vein

Phosphorus, calcium, magnesium, sodium, and potassium are stored where?

Bones

Carotid artery

Main artery bringing blood to the head

External jugular vein

Main vein draining the head + neck

Parathyroid glands are not _____.

palpable

Hyperthyroidism is disease in older ______.

cats

CN 1: olfactory nerve

Scent, pheromones: Flehmen Response allows pheromones + scents to contact the vomeronasal organ

CN II: Optic nerve

Vision: Responsible for carrying visual information from the retina to the brain.

CN III: Oculomotor nerve

• Controls extrinsic eye muscles

• Carries parasympathetic fibers to the pupillary constrictor muscles

Extrinsic eye muscles for CN III: Oculomotor nerve

• Dorsal rectus

• Ventral rectus

• Medial rectus

• Ventral oblique

CN IV: Trochlear nerve

Controls 1 extrinsic eye muscle (Dorsal oblique)